Device for electromagnetic characterisation of a tested structure

ABSTRACT

The invention concerns a device for electromagnetic characterisation of a tested structure ( 2 ), by evaluating, on a predetermined frequency band, distribution parameters of said structure ( 2 ) and parameters characteristic of the spurious rays of said structure ( 2 ), comprising an electric signal generator ( 4 ), means ( 8 ) for transmitting said electric signal to the tested structure ( 2 ), means ( 6 ) for analysing the signal transmitted by the generator ( 4 ) and signals reflected by the structure ( 2 ) and signals transmitted by the structure ( 2 ), the analysing means ( 6 ) comprising means for calculating said parameters. In addition, the electric signal generator ( 4 ) is a pulsed signal generator whereof the spectrum is at least as broad as said predetermined frequency band, and the analysing means ( 6 ) comprise means for temporal filtering of the signals it receives, to eliminate spurious signals.

[0001] The present invention relates to a device for electromagneticcharacterization of a tested structure, and to a corresponding process.

[0002] More precisely, the invention relates to a device forelectromagnetic characterization of a tested structure terminated byconnectors linked to transmission lines of any impedance, by evaluating,on a predetermined frequency band, distribution parameters of thisstructure and characteristic parameters of the spurious radiations ofthis structure. This device comprises an electrical signal generator,means of transmitting this electrical signal to the tested structure,means of analysis of the signal emitted by the generator, as well as ofthe signals reflected by the structure and of the signals transmitted bythe structure, the means of analysis comprising means of calculation ofthe distribution parameters of the tested structure and of thecharacteristic parameters of the spurious radiations.

[0003] Conventionally, such a device, used for example for theelectromagnetic characterization of an electrical connector, generallycomprises a network analyzer connected to the two terminals of theelectrical connector.

[0004] The network analyzer comprises a sinusoidal signal generatorwhose frequency can be adjusted within the predetermined frequency band.It transmits this signal to either of the two terminals of the connectorand receives in return a signal reflected by this terminal and a signaltransmitted by the other terminal.

[0005] However, the network analyzer also receives spurious signals atthe same frequency, stemming in particular from electromagnetic wavesemanating from a radiation of the characterization device and of thetested structure and backscattered by the walls of premises in which theelectromagnetic characterization device is placed.

[0006] The frequency of the spurious signals being the same as that ofthe signals to be analyzed, the network analyzer cannot differentiatebetween these signals. To obtain accurate measurements, it is thereforenecessary to place the electromagnetic characterization device and thetested structure in an anechoic chamber, which absorbs theelectromagnetic waves radiated.

[0007] Moreover, to characterize the tested structure over the entirepredetermined frequency band, the signal generator of the networkanalyzer must provide a multiplicity of successive sinusoidal signalsscanning said frequency band.

[0008] The invention aims to remedy these drawbacks by creating a devicecapable of accurately performing the electromagnetic characterizationmeasurements, while being simple and inexpensive.

[0009] The subject of the invention is therefore a device forelectromagnetic characterization of a tested structure terminated byconnectors linked to transmission lines of any impedance, by evaluating,on a predetermined frequency band, distribution parameters of thisstructure and characteristic parameters of the spurious radiations ofthis structure, comprising an electrical signal generator, means oftransmitting this electrical signal to the tested structure, means ofanalysis of the signal emitted by the generator, as well as of thesignals reflected by the structure and of the signals transmitted by thestructure, the means of analysis comprising means of calculation of thedistribution parameters and of the characteristic parameters of thespurious radiations of the tested structure, characterized in that theelectrical signal generator is a generator of a pulsed signal whosespectrum is at least as wide as said predetermined frequency band, thegenerator being adapted for emitting this pulsed signal at least once,and in that the means of analysis comprise means of temporal filteringof the signals which they receive, for the elimination of spurioussignals.

[0010] Thus, the electromagnetic characterization device according tothe invention makes it possible to characterize the tested structure,over the entire predetermined frequency band, by generating a singlespulsed signal whose spectrum covers this frequency band, it beingpossible for this pulsed signal to be emitted one or more times by thegenerator.

[0011] Moreover, the signals received in return by the means of analysisof the electromagnetic characterization device are also pulsed signals,be they signals reflected and transmitted by the tested structure orspurious signals.

[0012] Thus, the means of analysis furthermore comprising means oftemporal filtering of these signals, it is easy for them to eliminatethe spurious signals, without requiring the device to be placed in ananechoic chamber.

[0013] The electromagnetic characterization device according to theinvention can furthermore comprise one or more of the followingcharacterictics:

[0014] the tested structure being terminated by multiwire connectors,the device furthermore comprises propagation mode and impedance matchingmeans disposed between these multiwire connectors and the remainder ofthe device;

[0015] the tested structure being terminated by connectors each linkedto at least one two-wire line, the matching means comprise a pluralityof adapters of each two-wire line, disposed on either side of the testedstructure, each comprising a voltage splitting circuit and a two-wireconnection terminal formed by the two central conductors of two coaxialcables whose outer conductors are short-circuited;

[0016] the device furthermore comprises means of transmission of thepulsed signal alone, to the means of analysis for the provision of areference signal to them;

[0017] the width of the predetermined frequency band is greater than orequal to 1 GHz;

[0018] the pulsed signal is a pulsed signal of Gaussian general shape;

[0019] the means of analysis comprise a first path for processing thesignal emitted by the generator and the signal reflected by the testedstructure, comprising at least one reception path, and a second path forprocessing the signal transmitted by the tested structure comprising atleast one reception path;

[0020] the temporal filtering means comprise first means of selectionbetween predetermined instants of a part of the signals received by thefirst processing path, this part containing only the signal reflected bythe tested structure, and second means of selection betweenpredetermined instants of a part of the signals received by the secondprocessing path, this part containing only the signal transmitted by thetested structure;

[0021] means of prolongation by continuity of said part containing onlythe signal transmitted by the tested structure, for the reconstructionof this transmitted signal, are associated with said second means ofselection;

[0022] the tested structure is a connector of multiwire links;

[0023] the means of calculation comprise means of calculation of theamount of power radiated by the tested structure; and

[0024] the tested structure being a connector of multiwire links, themeans of calculation comprise means of calculation of the field radiatedby this connector, when the latter is used in the implementation of alink between an emitter and a receiver of electrical signals.

[0025] The subject of the invention is also a process forelectromagnetic characterization of a tested structure terminated byconnectors linked to transmission lines of any impedance, by evaluating,on a predetermined frequency band, distribution parameters of thisstructure and characteristic parameters of the spurious radiations ofthis structure, the process comprising the following steps:

[0026] the emission, at least once, by a generator of an electricalsignal toward the tested structure;

[0027] the reception of the signal emitted by the generator as well asof the signals reflected by the structure and of the signals transmittedby the structure, by means of analysis; and

[0028] the calculation by the means of analysis of the distributionparameters of the tested structure and of the characteristic parametersof the spurious radiations of this structure, characterized in that theelectrical signal is a pulsed signal of greater spectral width than saidpredetermined frequency band, and in that the process furthermorecomprises a step of temporal filtering of the signals received by themeans of analysis, for the elimination of spurious signals.

[0029] The invention will be better understood on reading the followingdescription, given merely by way of example and while referring to theappended drawings, in which:

[0030]FIG. 1 is a diagrammatic view of the general structure of a deviceaccording to a first embodiment of the invention;

[0031]FIG. 2 represents the time profile and the spectrum of a pulseprovided by a generator of the device of FIG. 1;

[0032]FIG. 3 diagrammatically represents the structure of means ofanalysis of the device of FIG. 1;

[0033]FIG. 4 is a diagrammatic view of the general structure of a deviceaccording to a second embodiment of the invention;

[0034]FIG. 5 is a diagrammatic view of means of matching the device ofFIG. 4;

[0035]FIG. 6 is a diagrammatic view of the general structure of a devicefor providing a reference signal to the means of analysis of FIG. 3;

[0036]FIGS. 7A to 7D represent the profile of a signal received andprocessed by a first processing path of the means of analysis of FIG. 3;

[0037]FIGS. 8A to 8D represent the profile of a signal received andprocessed by a second processing path of the means of analysis of FIG.3; and

[0038]FIG. 9 is a diagrammatic view of a link between an emitter and areceiver, using connectors tested by the device of FIG. 1.

[0039] The electromagnetic characterization device represented in FIG. 1comprises a tested structure 2 consisting of a connector of coaxialcables of 50 ohm impedance, a pulse generator 4 and means of analysis 6.

[0040] A first coaxial transmission cable 8 is disposed between thepulse generator 4 and the connector 2. It comprises an end 8 a connectedat the output of the pulse generator 4 and another end 8 b connected toa first terminal 2 ₁ of the connector 2.

[0041] A second coaxial transmission cable 10 is disposed between theconnector 2 and a load 12. An end 10 a of this second cable 10 isconnected to the load 12, while the other end 10 b of the second cable10 is connected to a second terminal 2 ₂ of the connector 2.

[0042] A probe 14 is disposed on the first transmission cable 8, so asto gather a signal emitted by the pulse generator 4 and a signalreflected by the connector 2.

[0043] A probe 16 is disposed on the second transmission cable 10, so asto gather a signal transmitted by the connector 2.

[0044] A third transmission cable 18 is disposed between the means ofanalysis 6 and the probe 14. A first end 18 a of this third cable 18 isconnected to a first reception path 20 of the means of analysis 6, whileits other end 18 b is connected to the probe 14.

[0045] A fourth transmission cable 22 is disposed between the means ofanalysis 6 and the probe 16. A first end 22 a of this fourthtransmission cable 22 is connected to a second reception path 24 of themeans of analysis 6, while its other end 22 b is connected to the probe16.

[0046] The device as described above is mounted as a forward setup.

[0047] It allows the first reception path 20 to receive the signalemitted by the pulse generator 4 and the signal reflected by theconnector 2 at the level of its first terminal 2 ₁. It furthermoreallows the second reception path 24 to receive the signal transmitted bythe connector 2 at the level of its second terminal 2 ₂.

[0048] It is however possible to swap the pulse generator 4 and the load12, so that the load 12 is connected to the end 8 a of the firsttransmission cable 8 and that the pulse generator 4 is connected to theend 10 a of the second transmission cable 10. In this case, the deviceis mounted as a reverse setup.

[0049] The reverse-mounted device allows the second reception path 24 toreceive the signal emitted by the pulse generator 4 and the signalreflected by the connector 2 at the level of its second terminal 2 ₂. Itfurthermore allows the first reception path 20 to receive the signaltransmitted by the connector 2 at the level of its first terminal 2 ₁.

[0050] The pulse generator 4 used is for example the generator known bythe reference PSPL2600C and marketed by the company PICOSECOND PULSELABS. This generator exhibits an output impedance of 50 ohms.

[0051] As is represented in FIG. 2, this pulse generator 4 provides apulsed signal 26 exhibiting a first part 28 of Gaussian shape of shortduration, followed by a second linear part 30 of small amplitude, buttending more slowly to 0.

[0052] It will be noted that the bandwidth of this pulsed signal 26 at−20 dB is greater than 1.5 GHz.

[0053] The probes 14 and 16 used are preferably of the PSPL 5520C typemarketed by the company PICOSECOND PULSE LABS. They exhibit an impedanceof 50 ohms and a bandwidth of greater than 3 GHz.

[0054] The transmission cables 8, 10, 18 and 22 used are of theconventional type. They exhibit an impedance of 50 ohms and allow thepropagation of the pulsed signal delivered by the generator 4 as well asof the pulsed signal reflected and of the pulsed signal transmitted bythe connector 2, without deforming their temporal shape and,consequently, without altering their spectral content.

[0055] The means of analysis 6 comprise for example a direct-samplingoscilloscope, such as the TDS 694C oscilloscope marketed by the companyTEKTRONIKS. This oscilloscope allows once-only acquisition of a signal,for a limited number of samples and a limited vertical resolution.

[0056] However, the means of analysis 6 preferably comprise asequential-sampling oscilloscope, such as the TDS 820 oscilloscopemarketed by the company TEKTRONIKS.

[0057] The use of such an oscilloscope requires that the pulse generator4 emit a plurality of identical pulsed signals at regular intervals.

[0058] The digital oscilloscope 6 then periodically taps off samples,according to a period slightly greater than the emission period of thepulsed signals. This samples tapping period is adjusted as a function ofthe total number of samples to be tapped off and the number of pulsedsignals to be emitted by the generator is equal to the number of samplesto be tapped off in the course of a measurement.

[0059] On the other hand, this oscilloscope allows the acquisition of asignal, with a number of samples and a vertical resolution which aremarkedly greater than those allowed by a direct-sampling oscilloscope.

[0060] The means of analysis 6 also comprise, for example, amicrocomputer linked to the oscilloscope, to perform a part of theprocessing and calculations allowing the determination of thedistribution parameters of the connector 2 and of the characteristicparameters of the spurious radiations of this connector, such as, inparticular the power and the field radiated by the connector 2.

[0061] With reference to FIG. 3, the first and second reception paths 20and 24 of the means of analysis 6 of the forward-mounted device withelectromagnetic characteristics receive electrical signals picked up bythe probes 14 and 16. They output digital signals obtained by samplingthese electrical signals.

[0062] The signal provided by the first reception path 20, whichcontains the signal 26 emitted by the pulse generator 4, the signalreflected by the connector 2 and spurious signals, is transmitted to aninput of a subtractor 34. A second input of the subtractor 34 isconnected to a RAM type memory 36, furthermore connected to the firstinput 20. In this memory 26 are stored data relating to the signal 26emitted by the pulse generator 4.

[0063] These data are recorded during a step of provision of a referencesignal, which will be described later.

[0064] The subtractor 34 outputs a signal to a filter 38 of the means 32of temporal filtering. This filter performs a temporal selection of apart of said signal, between two predetermined instants T0 and T1.

[0065] The first reception path 20, the subtractor 34 and the filter 38constitute a first processing path of the analysis means 6.

[0066] The processing of the signal originating from the first receptionpath 20, by this first processing path will be described with referenceto FIGS. 7A to 7D. At the end of processing, it makes it possible toobtain just the signal reflected by the connector 2.

[0067] The signal output by the filter 38 is then transmitted by thetemporal filtering means 32 to a spectrum calculation circuit 40.

[0068] The spectrum calculation circuit 40 is furthermore connected tothe memory 36, thus allowing it to also receive as input the signal 26emitted by the pulse generator 4.

[0069] The circuit 40 is adapted for calculating the spectrum of asignal provided as input.

[0070] In the filtering means 32, the sampled signal provided by thesecond input 24 of the analysis means 6, which comprises the signaltransmitted by the connector 2 and the spurious signals, is transmittedto a filter 42 of the temporal filtering means 32, performing a temporalselection of a part of this signal between two predetermined instants T2and T3.

[0071] The signal output by the filter 42 is transmitted by the temporalfiltering means 32 to means 44 of prolongation by continuity of thissignal.

[0072] The second reception path 24, the filter 42 and the means 44 ofprolongation by continuity constitute a second processing path of theanalysis means 6.

[0073] The processing of the signal originating from the secondreception path 24, by this second processing path, will be describedwith reference to FIGS. 8A to 8D. At the end of processing, it makes itpossible to obtain just the signal transmitted by the connector 2.

[0074] The signal output by the means 44 of prolongation by continuityis transmitted to the spectrum calculation circuit 40.

[0075] The spectrum calculation circuit 40 is connected at output to acalculator 41 which it provides with the spectral coefficients of thesignal 26 emitted by the pulse generator 4, of the signal reflected bythe connector 2 and of the signal transmitted by this same connector 2,after having performed the calculation of their spectrum.

[0076] The calculator 41 is adapted for providing the distributionparameters of the connector 2 as well as the characteristic parametersof the spurious radiations of this connector, on the basis of thespectral coefficients.

[0077] It comprises means 41 a of calculation of the distributionparameters of the connector 2, means 41 b of calculation of the powerradiated by the connector 2 and means 41 c of calculation of the fieldradiated by the connector 2. Its manner of operation will be detailedsubsequently.

[0078] The analysis means 6 represented in FIG. 3 have been described inaccordance with the device represented in FIG. 1, that is to say as aforward setup.

[0079] When the electromagnetic characterization device is mounted as areverse setup, the first reception path 20 should be linked to thefilter 42 and the second reception path 24 to the subtractor 34 and tothe RAM memory 36.

[0080] Thus, the analysis means 6 are adapted so that the firstprocessing path is constituted by the second reception path 24, thesubtractor 36 and the filter 38, and so that the second processing pathis constituted by the first reception path 20, the filter 42 and themeans 44 of prolongation by continuity. This adaptation is automatic andperformed by software means.

[0081] The electromagnetic characterization device represented in FIG. 4relates to another possible embodiment of the invention. It comprises,this time, a tested structure 2 consisting of a connector of multiwirelinks, whose impedance is different from 50 ohms. In the description ofFIG. 4, we shall limit ourselves to the case of a connector of two-wirelinks of 100-ohm impedance.

[0082] In this embodiment, in which the device is mounted as a forwardsetup, the pulse generator 4, the means of analysis 6, the load 12, theprobes 14 and 16, the third and fourth transmission cables 18 and 22,are identical to those described with reference to FIG. 1 and aredisposed in the same manner.

[0083] By contrast, the connector 2 being a connector of two-wire links,the first and second transmission cables 8, 10 cannot be linked directlyto the terminals 2 ₁ and 2 ₂ of this connector.

[0084] Thus, the first transmission cable 8 is connected on the onehand, by its end 8 a to the pulse generator 4, and on the other hand byits end 8 b to a first adapter 46. The second transmission cable 10 is,for its part, connected on the one hand, to the load 12 by its end 10 aand on the other hand to a second adapter 48 by its end 10 b.

[0085] The first adapter 46 is furthermore connected to the terminal 2 ₁of the two-wire connector 2 by means of a two-wire link 50 and thesecond adapter 48 is furthermore connected to the terminal 2 ₂ of thetwo-wire connector 2 by means of a two-wire link 52.

[0086] The first and second adapters 46 and 48 have to carry outadaptation between a coaxial mode of propagation of a signal in thecables 8 and 10 and a differential mode of propagation in the two-wirelinks 50 and 52.

[0087] Moreover, since the connector 2 exhibits an impedance of 100ohms, while the generator 4, the analysis means 6, the cables 8, 10, 18and 22, the probes 14 and 16 each have an impedance of 50 ohms, theadapters 46 and 48 must furthermore carry out impedance matching from 50to 100 ohms.

[0088] Finally, the adapters 46 and 48 must be bidirectional.

[0089] These two adapters being identical, one of them, for example theadapter 46, is represented in FIG. 5. It comprises, for example, avoltage splitting circuit 54.

[0090] This circuit 54 comprises a coaxial input terminal 56, forreceiving the end 8 b of the first transmission cable 8, and two coaxialoutput terminals 58, to which are connected two semi-rigid coaxialcables 60.

[0091] The outer conductors of the two coaxial cables 60 are soldered attheir opposite end to the output terminals 58 so as to short-circuitthem and thus carry out the impedance matching. The central core of eachof these two coaxial cables 60 is adapted for receiving one of the twowires of the two-wire link 50 or 52.

[0092] The device described with reference to FIGS. 4 and 5 may beadapted simply to allow the characterization of a structure terminatedby connectors of multiwire links with 2n wires, n being any integernumber.

[0093] Specifically, in this case, a multiwire link may be regarded as ntwo-wire links. Each of these n two-wire links is then connected to anadapter such as that described with reference to FIG. 5.

[0094] The electromagnetic characterization device then comprises nadapters such as the adapter 46, n adapters such as the adapter 48, ncables such as the cable 8, n cables such as the cable 10, n cables suchas the cable 18, n cables such as the cable 22, n probes such as theprobe 14, n probes such as the probe 16 and n loads such as the load 12.

[0095] It is then necessary to provide means of analysis 6 comprising nreception paths such as the reception path 20 and n reception paths suchas the reception path 24.

[0096] The device for providing a reference signal to the analysis means6 and which is represented in FIG. 6 comprises the pulse generator 4connected to the end 8 a of the first transmission cable 8. The end 8 bof the first transmission cable is connected to the load 12.

[0097] The probe 14 is disposed on the first transmission cable 8 at thelevel of its end 8 b and is connected to the end 18 b of the thirdtransmission cable 18.

[0098] The end 18 a of this third transmission cable 18 is connected tothe first reception path 20 of the analysis means 6.

[0099] The manner of operation of the means of analysis 6 of the devicerepresented in FIG. 1, of the device represented in FIG. 4 or of thedevice represented in FIG. 6, will now be described.

[0100] The means of analysis 6 perform the calculation of fourdistribution parameters S₁₁, S₂₁, S₁₂ and S₂₂ of the tested structure 2.The coefficients S₁₁ and S₂₁ respectively represent the reflectioncoefficient and the transmission coefficient of the tested structure 2,when the device is mounted as a forward setup. The coefficients S₂₂ andS₁₂ respectively represent the reflection coefficient and thetransmission coefficient of the tested structure 2, when the device ismounted as a reverse setup.

[0101] Additionally, the means of analysis perform the calculation ofthe amount η of power lost by the connector 2 and the field {right arrowover (E)} radiated by this connector 2, which are deduced from thedistribution parameters S₁₁, S₂₁, S₁₂ and S₂₂.

[0102] Firstly, during a step of provision of a reference signal to theanalysis means 6, implemented in the calibration device represented inFIG. 6, the first reception path 20 of the analysis means 6 receives thepulsed signal 26 emitted by the pulse generator 4 and picked up by theprobe 14. After having been sampled by the first reception path 20 ofthe analysis means 6, this pulsed signal is stored in the RAM memory 36.

[0103] For the calculation of the reflection coefficients S₁₁ and S₂₂,depending on whether the device is mounted as a forward or reversesetup, the analysis means 6 receive as input from the subtractor 34, asignal, such as that represented in FIG. 7A.

[0104] This signal comprises the pulsed signal 26 emitted by the pulsegenerator 4 whose first part 28 of Gaussian shape is received by theanalysis means 6, before a predetermined instant T0. This signalfurthermore comprises the pulsed signal 62 reflected by the connector 2,received by the analysis means 6 between the instant T0 and apredetermined instant T1.

[0105] Finally, this signal comprises spurious echoes 64, received bythe analysis means 6 beyond the instant T1.

[0106] With reference to FIG. 7B, the signal provided by the subtractor34 to the filter 38, after subtraction of the pulsed signal 26 stored inthe RAM memory 36, comprises a residual signal 66 of the Gaussian partof the pulsed signal 26. This residual signal 66 is received by theanalysis means 6 before the instant T0. Between the instants T0 and T1,the signal comprises just the reflected pulsed signal 62 from which hasbeen subtracted the second, linear, part 30 of the pulsed signal 26.Beyond the instant T1, this signal comprises the spurious echoes 64.

[0107] This signal is thereafter modulated in the filter 38 by a timefunction represented in FIG. 7C. This modulating function is a gatingfunction taking the value 1 between the instants T0 and T1 and zeroeverywhere else.

[0108] Consequently, as represented in FIG. 7D, the signal provided tothe circuit 40 by the analysis means 6, now comprises only the reflectedsignal 62.

[0109] For the calculation of the transmission coefficients S₂₁ and S₁₂,the temporal filtering means 32 receive as input from the filter 42, asignal, as represented in FIG. 8A. This signal comprises the pulsedsignal 68 transmitted by the connector 2, exhibiting a first part 70 ofGaussian shape received by the analysis means 6 between predeterminedinstants T2 and T3, and a second, linear, part 72 extending beyond theinstant T3. This signal furthermore comprises spurious signals 74received by the analysis means 6 beyond the instant T3, but superimposedon the second part 72 of the transmitted signal 68.

[0110] In the filter 42, the signal represented in FIG. 8A is modulatedby a function, as represented in FIG. 8B.

[0111] This modulating function is a gating function equal to 1 betweenthe instants T2 to T3 and zero everywhere else.

[0112] Thus, as represented in FIG. 8C, the signal provided to the means44 of prolongation by continuity is a signal ridded of the spurioussignals 74, but exhibiting a discontinuity at the instant T3.

[0113] As represented in FIG. 8D, the means 44 of prolongation bycontinuity perform a linear prolongation by continuity of the signalrepresented in FIG. 8C. Specifically, this truncated signal issupplemented with a linear part, the slope of which is equal to theslope of the truncated signal in the neighborhood of the instant T3.

[0114] Thus, the signal represented in FIG. 8D, provided to the circuit40 by the analysis means 6, now comprises only the signal transmitted 68by the connector 2.

[0115] The calculation of the spectral coefficients of the pulse 26emitted by the pulse generator 4, of the pulse reflected by theconnector 2 and of the pulse transmitted by this same connector 2, isthen performed by the spectrum calculation circuit 40. This calculationis regarded as conventional and will therefore not be detailed.

[0116] The calculation of the parameters S₁₁, S₂₁, S₁₂ and S₂₂ by themeans of calculation 41 a of the calculator 41 requires theimplementation of a prior calibration process, so as to compensate forsystematic errors dependent on the structure of the electromagneticcharacterization device, as represented in FIG. 1 or in FIG. 4.

[0117] This calibration process, as well as the calculation of thedistribution parameters by the calculation means 41 a, are also regardedas conventional and will not be described.

[0118] For example, for the device represented in FIG. 1, thecalibration process generally used is a conventional calibration processof SOLT (Short Open Load Thru) type.

[0119] The calibration process implemented for the device represented inFIG. 4 is a calibration process of TRL (Thru, Reflect, Line) type. Sucha process for this calibration, as well as a process for calculating thedistribution parameters for the device represented in FIG. 4, isdescribed in the article entitled “Improving TRL calibrations of vectornetwork analyzers”, by Don Metzger, published in Microwave Journal, May1995, pages 56 to 68.

[0120] Thereafter, the calculation means 41 b perform the calculation ofthe amount η of power radiated by the connector 2. This amount is givenby the following formula (in a forward setup):

η=1−|S _(11 |) ² −|S _(21|) ².

[0121] The calculation means 41 c perform the calculation of the field{right arrow over (E)} radiated by the connector 2, when the latter isused in the implementation of a link between an emitter and a receiver,as represented in FIG. 9. The setup represented in this figure comprisesa transmission line 74 of any impedance, of length L and of diameter d,connected on the one hand to an emitter 76 by means of a connector 2 a,like the connector 2, and is connected to a receiver 78 by means ofanother connector 2 b like the connector 2.

[0122] This transmission line 74 is furthermore disposed at a height h,with respect to a ground plane 80 of the setup.

[0123] The connectors 2 a and 2 b may be likened to generators ofcommon-mode currents I_(c1) and I_(c2.)

[0124] The common-mode current I_(c1) of the connector 2 a near theemitter 76, is given by the following formula:$I_{cl} = {{\sqrt{\frac{2\quad \eta}{z_{c}},}{where}\quad z_{c}} = {60\quad {\ln ( \frac{4h}{d} )}}}$

[0125] is the characteristic impedance of the transmission line 74.

[0126] The common-mode current I_(c2) of the connector 2 b near thereceiver 78, is given by the following formula:

I _(c2)=(1−{square root}{square root over (η)})I _(c1)e^(−jβL)

[0127] where ${\beta = \frac{2\quad \pi \quad f}{\lambda}},$

[0128] with f and λ being the frequency and the wavelength of a currentpassing through the transmission line 74.

[0129] The far field {right arrow over (E)}₁ radiated by the setup anddue to the presence of the connector 2 a, is then estimated in polarcoordinates, taking the setup as origin, by the following relation:$\begin{matrix}{\overset{arrow}{E_{1}( {r,\theta} )} = {j\frac{k}{4\quad \pi}z_{o}{\psi (r)}\sin \quad \theta \frac{\sin \quad X_{1}}{X_{1}}I_{c1}L{.2}\quad \sin \quad Y\quad {\overset{arrow}{U}}_{e}\quad {with}}} \\{X_{1} = {\frac{k\quad L}{2}( {{\cos \quad \theta} - 1} )\quad {and}}} \\{Y = {\frac{2\quad \pi \quad h}{\lambda}\quad \sin \quad \theta \quad {where}}} \\{{Z_{o} = {120\quad \pi}},\quad {{\psi (r)} = \frac{e - {j\quad k\quad r}}{r}},{k = {\frac{2\quad \pi \quad f}{c}.}}}\end{matrix}$

[0130] The far field {right arrow over (E)}₂ radiated by the setup anddue to the presence of the connector 2 b is estimated by the followingrelation: $\begin{matrix}{\overset{arrow}{E_{1}( {r,\theta} )} = {j\frac{k}{4\quad \pi}z_{o}{\psi (r)}\sin \quad \theta \frac{\sin \quad X_{1}}{X_{1}}I_{c1}L{.2}\quad \sin \quad Y\quad {\overset{arrow}{U}}_{e}\quad {with}}} \\{X_{2} = {\frac{k\quad L}{2}( {{\cos \quad \theta} + 1} )\quad {and}}} \\{Y = {\frac{2\quad \pi \quad h}{\lambda}\quad \sin \quad \theta \quad {where}}} \\{{Z_{o} = {120\quad \pi}},\quad {{\psi (r)} = \frac{e - {j\quad k\quad r}}{r}},{k = \frac{2\quad \pi \quad f}{c}}}\end{matrix}$

[0131] Thus, the total radiated field becomes: $\begin{matrix}{\overset{arrow}{E_{1}( {r,\theta} )} = {{j\frac{k}{4\quad \pi}z_{o}{\psi (r)}\sin \quad \theta \frac{\sin \quad X_{1}}{X_{1}}I_{c1}L{.2}\quad \sin \quad Y\quad U_{e}} +}} \\{j\frac{k}{4\quad \pi}z_{o}{\psi (r)}\sin \quad \theta \frac{\sin \quad X_{2}}{X_{2}}( {1 - \sqrt{\eta}} )I_{c1}^{{- j}\quad \beta \quad L}L{.2}\quad \sin \quad {Y( {- {\overset{arrow}{U}}_{e}} )}}\end{matrix}$

[0132] From this, one deduces the value of the modulus of the totalfield radiated by the setup in the presence of the connectors 2 a and 2b, given by the following relation: $\begin{matrix}{{{r\quad {E( {r,\theta} )}}} = {{{\frac{60\pi}{c}f\quad {LI}_{c1}\quad \sin \quad \theta \quad 2\quad \sin \quad Y}} \times}} \\\sqrt{( {( {\frac{\sin \quad X_{1}}{X_{1}} - \frac{\sin \quad X_{2}}{X_{1}}} )( {1 - \sqrt{\eta}} )\cos \quad \beta \quad L} )^{2} + ( {( \frac{\sin \quad X_{2}}{X_{2}} )( {1 - \sqrt{\eta}} )\sin \quad \beta \quad L} )^{2}}\end{matrix}$

[0133] It is clearly apparent that an electromagnetic characterizationdevice according to the invention makes it possible to characterize thetested structure 2 over the entire predetermined frequency band, withthe aid of the pulse 26 emitted by the pulse generator 4.

[0134] Specifically, the analysis means 6 possess means 32 of temporalfiltering allowing discrimination of the pulse emitted by the pulsegenerator 4, of the pulse reflected by the connector 2, of the pulsetransmitted by this same connector 2, and the rejection of spurioussignals.

[0135] Moreover, they comprise means of calculation of the dispersionparameters of the connector 2, of the amount of power radiated by theconnector 2 and of the field radiated by this connector 2.

1. A device for electromagnetic characterization of a tested structure(2) terminated by connectors linked to transmission lines of anyimpedance, by evaluating, on a predetermined frequency band,distribution parameters of this structure (2) and characteristicparameters of the spurious radiations of this structure (2), comprisingan electrical signal generator (4), means (8) of transmitting thiselectrical signal to the tested structure (2), means (6) of analysis ofthe signal emitted by the generator (4), as well as of the signalsreflected by the structure (2) and of the signals transmitted by thestructure (2), the means of analysis (6) comprising means (41) ofcalculation of the distribution parameters and of the characteristicparameters of the spurious radiations of the tested structure,characterized in that the electrical signal generator (4) is a generatorof a pulsed signal (26) whose spectrum is at least as wide as saidpredetermined frequency band, the generator being adapted for emittingthis pulsed signal (26) at least once, and in that the means of analysis(6) comprise means (32) of temporal filtering of the signals which theyreceive, for the elimination of spurious signals (64, 74).
 2. The devicefor electromagnetic characterization as claimed in claim 1,characterized in that, the tested structure (2) being terminated bymultiwire connectors, the device furthermore comprises propagation modeand impedance matching means (46, 48) disposed between these multiwireconnectors and the remainder of the device.
 3. The device forelectromagnetic characterization as claimed in claim 2, characterized inthat, the tested structure (2) being terminated by connectors eachlinked to at least one two-wire line (50, 52), the matching means (46,48) comprise a plurality of adapters of each two-wire line, disposed oneither side of the tested structure (2), each comprising a voltagesplitting circuit (57) and a two-wire connection terminal (58, 60)formed by the two central conductors of two coaxial cables (60) whoseouter conductors are short-circuited.
 4. The device for electromagneticcharacterization as claimed in any one of claims 1 to 3, characterizedin that it furthermore comprises means of transmission (8, 14, 12, 18)of the pulsed signal (26) alone, to the means of analysis (6) for theprovision of a reference signal for them.
 5. The device forelectromagnetic characterization as claimed in any one of claims 1 to 4,characterized in that the width of the predetermined frequency band isgreater than or equal to 1 GHz.
 6. The device for electromagneticcharacterization as claimed in any one of claims 1 to 5, characterizedin that the pulsed signal (26) is the pulsed signal of Gaussian generalshape.
 7. The device for electromagnetic characterization as claimed inany one of claims 1 to 6, characterized in that the means of analysis(6) comprise a first path (20, 34, 48) for processing the signal emittedby the generator (4) and the signal reflected by the tested structure(2), comprising at least one reception path (20), and a second path (24,42, 44) for processing the signal transmitted by the tested structure(2) comprising at least one reception path (24).
 8. The device forelectromagnetic characterization as claimed in claim 7, characterized inthat the temporal filtering means (32) comprise first means (38) ofselection between predetermined instants of a part of the signalsreceived by the first processing path (20, 34, 38), this part containingonly the signal reflected by the tested structure (2), and second means(42) of selection between predetermined instants of a part of thesignals received by the second processing path (24, 42, 44), this partcontaining only the signal transmitted by the tested structure (2). 9.The device for electromagnetic characterization as claimed in claim 8,characterized in that means (44) of prolongation by continuity of saidpart containing only the signal transmitted by the tested structure (2),for the reconstruction of this transmitted signal, are associated withsaid second means of selection (42).
 10. The device for electromagneticcharacterization as claimed in any one of claims 1 to 9, characterizedin that the tested structure (2) is a connector of multiwire links. 11.The device for electromagnetic characterization as claimed in any one ofclaims 1 to 10, characterized in that the means of calculation (41)comprise means (41 b) of calculation of the amount of power radiated bythe tested structure (2).
 12. The device for electromagneticcharacterization as claimed in claim 11, characterized in that, thetested structure (2) being a connector of multiwire links, the means ofcalculation (41) comprise means (41 c) of calculation of the fieldradiated by this connector (2), when the latter is used in theimplementation of a link between an emitter (76) and a receiver (78) ofelectrical signals.
 13. A process for electromagnetic characterizationof a tested structure (2) terminated by connectors linked totransmission lines of any impedance, by evaluating, on a predeterminedfrequency band, distribution parameters of this structure (2) andcharacteristic parameters of the spurious radiations of this structure(2), the process comprising the following steps: the emission, at leastonce, by a generator (4) of an electrical signal toward the testedstructure (2); the reception of the signal emitted by the generator (4)as well as of the signals reflected by the structure (2) and of thesignals transmitted by the structure (2), by means of analysis (6); andthe calculation by the means of analysis (6) of the distributionparameters of the tested structure (2) and of the characteristicparameters of the spurious radiations of this structure (2),characterized in that the electrical signal is a pulsed signal (26) ofgreater spectral width than said predetermined frequency band, and inthat the process furthermore comprises a step of temporal filtering ofthe signals received by the means of analysis (6), for the eliminationof spurious signals (64, 74).